Three-dimensional textiles for sandwich structures are known. Such textiles have two sheets connected by a plurality of extensible threads. During manufacturing, the extensible threads and the inner surfaces of the sheets are coated with a resin. The sheets are then moved apart by the required distance so that the extensible threads extend generally perpendicularly to both sheets. The resin is then allowed to cure, thereby creating a sandwich structure of relatively high stiffness yet being relatively light weight. Additional load carrying capacity, hence usefulness, may be added to this sandwich structure by adhering face sheets to the outer face of each sheet in a secondary process, the adhesion generally being achieved by the use of film adhesives, normally a thermoset adhesive.
Difficulty has been experienced in achieving reasonable perpendicularity of the extensible threads and ensuring flat face sheets. The known processes for achieving this are slow and relatively complex, thus making the composite sandwich structure so produced relatively expensive. It also means the process is quite slow, making it difficult for mass production.
Furthermore, the known manufacturing techniques are not suitable for large or complex shapes, thereby restricting their use.
It is therefore an object of the present invention to provide a method of manufacturing composite sandwich structures which at least in part addresses the problems of the known methods.
A further object is to produce a composite sandwich structure from the new method.